Electromagnetic energy can be used to sense or affect objects from a distance. One application is the stimulation of crude oil reservoirs for oil production.
Various methods have been developed for recovery of residual oil. For example, U.S. Pat. No. 2,799,641 discloses the use of direct current to stimulate an area around a well, and using electro-osmosis for oil recovery. Another example of electro-osmosis is described in U.S. Pat. No. 4,466,484, wherein direct current is used to stimulate a reservoir.
U.S. Pat. No. 3,507,330 discloses a method for stimulating the area near a well bore using electricity passed upwards and downwards in the well using separate sets of electrodes. U.S. Pat. No. 3,874,450 discloses a method for dispersing an electric current in a subsurface formation by an electrolyte. U.S. Pat. No. 4,084,638 discloses high-voltage pulsed currents in two wells to stimulate an oil-bearing formation.
U.S. Pat. No. 6,427,774 teaches recovering oil soil and rock formations using pulsed electro-hydraulic and electromagnetic discharges that produce acoustic and coupled electromagnetic-acoustic vibrations.